Apparatus for the production of music



Oct. 3, 1933. B. F. MIESSNER APPARATUS FOR THE PRODUCTION OF MUSIC Filed Nov. 6, 1931 IN V EN TOR,

A ORNEY.

-. described. In many forms Patented Oct. 3, 1933 UNITED STATES PATENT OFFICE Benjamin F. Miessner, Millburn, N. J., assignor 'to Miessner Inventionsylna, a corporation New Jersey- Application November 6, 1931. Serial No. 573,319

12 Claims.

This invention relates to methods and apparatus for producing music by the translation into electric oscillations of the vibrations of strings or other vibrators and by the use of such oscillations for the actuation of further apparatus; and more specifically to useful arrangements of vibrators, and of vibrators and translating devices, in a system or instrument wherein such translation is employed. Such systems and instruments are described and claimed broadly in my co-pending application, Serial Number 512,399, filed January 30, 1931.

The instant invention is concerned primarily with coupling between the different vibrators of a group in an instrument or system of the class of conventional musical instruments employing a plurality of vibrators, of which the piano is a'noteworthy example, a form of such coupling results from the passage of the vibrators, or strings, over a bridge and the support of this bridge, by a vibratile diaphragm-like structure or resonator intended to efiect vibration-sound translatione. g., the soundboard of the piano. While both the bridge and its supporting structure comprise the coupling means, the supporting struc-- ture is the predominate factor in determining the degree of the coupling, such coupling being very high between vibrators connected to a bridge totally unsupported (excepting by engagement with the vibrators), and negligible or non-existent between vibrators connected to a substantially rigidly supported bridge.

The effect of this inter-vibrator coupling on the characteristics of the output tones varies from one type of instrument to another; but in an instrument of the piano type this coupling has a definite eiiect on the dynamics of the tones. By such dynamics I expressly intend to exclude the main or predominate harmonic structure of the tones (i. e., that which persists without sensible change throughout the duration of the tone) but particularly to include all the peculiar characteristics attendant upon tone commencement, such as noises due to impact of hammer and string, momentarily high initial amplitude, and a momentary initial complement of extra partial tones (particularly of higher frequencies) and to include the wide range, and nicety of variation, of responsivity of the tone in various respects, including amplitude, to the manner of excitation or key depression. It would appear that at least two actions of such coupling were of significance in contributing to the net effect: one, the vibration of other vibrators induced by vibration of one directly excited; and the other, the modification of the vibration of an excited vibrator by itscoupling to other vibrators, particularly at and immediately following its excitation.

In the co-pending application above referred to it has been shown that a variety of forms of produced music can be readily effected if the vibrations of a plurality of vibrators are translated, instead oi. directly into sound waves, into electric oscillations and these in turn into sound waves. lation, replacing the usual direct mechanicoacoustic translation, dispenses with the fundamental requirement for a resonator; and in the co-pending application above referred to I showed an instrument without a resonator, thus avoiding direct radiation of soundwaves to the confusion of the player of the instrument, who obviously should hear only the sounds produced by the controlled mechanico-electro-acoustic translation; and avoiding the extra damping of the vibrators produced by extraction therefrom of vibratory energy for direct translation into sound energy. I have found, however, that a still greater range of musical efiects may be produced from a plurality of vibrators if in combination with mechanico-electro-acoustic trans lation there be provided some form of intervibrator coupling.

Accordingly it is one object of my invention to provide, in combination with instruments without resonators but with mechanico-electra-acoustic translation, means for modifying the output tone characteristics, and particularly the dynamics of the tones.

It is a further object of the invention to provide, in an instrument of the class described, means and methods for superimposing, on the electric oscillations produced by the normal vibration or each vibrator, other oscillations harmonically related thereto. A further-obj act is the provision, in such an instrument, of means and methods for introducing into the initial oscillations components of harmonically related frequencies and other particular characteristics. A still further object is the provision of an instrument into the tones of which the various characteristics abovementioned may be introduced, or not, at will.

It is another object of the instant invention to provide novel means and methods for effecting inter-vibrator coupling in such an instrument.

It is another object to provide an instrument Such mechanico-electro-acoustic transin which the vibrators are coupled together and in which the vibrations of each vibrator, whether directly excited or produced by coupling to a directly excited vibrator, may be made available for use by translation into electric oscillations. It is a further object to provide such an instrument without appreciable direct sound output.

In the detailed description of my invention, hereinafter set forth, reference is had to the accompanying drawing, of which:

Figure 1 is a partial plan view of a musical instrument embodying my invention, the figure also including a diagrammatic view of certain electrical and electro-acoustic apparatus useful therewith;

Figure 2 is a partial cross-sectional view taken along the line 2-2 of Figure 1;

Figure 3 is a further fractional plan view of an instrument of the type shown in Figure 1, in which certain details not appearing in the earlier figure are shown;

Figure 4 is a partial cross-sectional view taken along the line 4-4 of Figure 1.

In Figures 1 and 2 I show a plurality of strings 1, strung as in a conventional piano from tuning pins (not shown), under capo or pressure bar 2, over a bridge 3 hereinafter more fully discussed, and over ledge 4 in plate 5 to hitch pins 6. Plate 5 and capo 2, with other members outside the scope of the figure, may of course form a single, integrally cast frame or plate, as is well understood. Below each string may be provided a hammer 8 for setting the string into vibration. The hammers 8 may be actuated by the conventional piano action and keys.

Bridge 3 is shown afilxed to and supported by a plurality of strips 11, preferably of relatively small cross-section. These strips may be affixed at their ends to rim 12 and rigid rim-beam 13; and are preferably in slight compression between their end supports and slightly bowed toward the strings, the better to resist the downward pressure of the latter, which will be seen to bear down on the bridge in the usual manner. Strips 11 form the structure supporting the bridge 3; they therefore determine the degree of coupling eflfected between the several strings 1. In general, the more strips, or the stiffer each strip, the less will be the degree of coupling effected. I have preferred to employ strips of wood approximately three-quarters of an inch square in crosssection and evenly spaced apart by a distance of about four to six inches; these figures are susceptible of wide modification, however, according fo the size of the instrument and to the degree of coupling, or magnitude of the abovementioned eifects of the coupling, which may be desired in a given case, as will be understood.

It is convenient to string the bass strings over a separate bridge as in the usual piano. The strips 11 shown in Figures 1 and 2 may be made available as a portion of the coupling means for strings so strung as well as those'strung over the main bridge, as I have shown in- Figure 3. Therein appears plate or frame 5, main bridge 3, rim 12 and strips 11. The separate bass bridge 3 may be aflixed to the strips 11 through an aperture in plate or frame 5, as customarily provided for connection of such bridge to the conventional soundboard.

Obviously the entire coupling means, comprising bridges 3 and 3' and the strips 11, forms a skeleton structure-Le, one in which the total surface is small and is interspersed with relativenear bridge 3.

ly large apertures. Such a structure is a poor radiator of sound and consequently the direct acoustic output of an instrument constructed in accordance with Figures 1 and 2 is very low. It may be desirable, however, still further to reduce it. For this purpose I have shown in Figure 2, above and beneath the strings, acoustic shielding 19, which may be in the form of sheets of felt or other soft and/or sound-absorbing material, such forexample as is sold under the trade name of Celotex. This shielding may, for example, be carried by top and bottom boards 18 and 17, respectively, these being fastened to the rim.

I have shown an instrument without a resonator, and have substantially eliminated direct sound output from the instrument, to the end that only the mechanico-electro-acoustic chain of translation shall be effective, and that the control over output tone effected by operating in various ways upon the electric oscillations shall be complete.

For translating the vibrations of the strings into electric oscillations I show a mechanicaelectric translating system having portions in spaced relation to the strings. This may include for example conductive strip -7, cemented to the top edge of insulating strip 9 and passing under a vibratable portion of each string, preferably Such strip construction is described and claimed in the U. S. Patent 1,915,859,

issued June 2'7, 1933, to myself and Charles T.

Jacobs. In general the strip 7 may be spaced approximately as close to the several strings as possible without causing contact of any string therewith under conditions of maximum vibration of such string. The strip 7 may be retained in proper position by the mounting of insulating strip 9 to frame 5, as by brackets 10. Strip 7 may be connected to the grid of vacuum tube 20, whose cathode may be energized in any suitable manner, as by battery 21; and whose anode current may be supplied from a tap on battery or other current source 22. The grid of tube 20 may be connected to the negative terminal of battery or source 22 through high resistance 23; and a condensively by-passed resistor 24 may be provided between the cathode of tube 20 and such negative terminal of battery or source 22 for the biasing of the grid of tube 20 by the flow of anode current through such resistor, as will be understood. In the output circuit of tube 20 may be provided amplifier 25, volume control 26, further amplifier 27 if desired, and loudspeaker 28. The positive terminal of battery or source 22 may be connected to the frame 5 and there through to the individual strings 1; and such connection may be conveniently madethrough the capacity between strip 7 and the portion of the string opposite such strip, in accordance with the frequency, waveform and relative amplitude of such portion; and the total capacity between strip 7 and all the strings will be likewise varied, but in reduced degree. This total capacity, by

virtue of its connection in series with resistance 23 and battery or source 22, contains-a relatively fixed charge; and the oscillatory variations thereplied 'to creasing the rate of damping in produced as above mentioned cause the voltage across the capacity, and hence that across resistance 23, to vary similarly. There is thus apthe input of tube 20 an A. C. voltage of frequency, waveform and relative amplitude corresponding respectively to those characteristics of the vibration of the mentioned portion or portions of the vibrated string or strings. By this tube such voltage is amplified; and it may be further amplified by amplifiers 25 and 2'7, controlled in respect of absolute amplitude by volume control 26, and translated into sound by loudspeaker 28. l

The coupling between the strings produces, as above mentioned, peculiar tonal effects; it also has some effect in increasing the rate of damping of thevibration of a struck string. For elimination at times of such tonal effects, and for deof the strings, it may frequently be desired substantially to elimihate the coupling between strings. This may be accomplished by locking the bridge; or making it relatively immobile-i. e., by defeating the action of its supporting system in permitting it to vibrate, particularly vertically.

In Figure 1 and. indetail in Figure 4 I have shown a system employing electromagnets 40 rigidly aflixed to the frame 5. These magnets. when energized by current, as from battery or source 41 through switch 42, attract into contact with their poles 43 armature 44, carried by spring 45 which normally holds armature 44 slightly out of contact with the poles. Spring 45 may be affixed to the bottom of bridge 3 as shown, rendering armature 44 substantially immovable vertically with respect to bridge 3 but sufficiently movable horizontally to clear or to engage poles 43 of the electromagnets, according as switch 42 is open or closed. Thus upon closing of switch 42 the.bridge is rendered substantially incapable of executing vertical vibration. While I have illustrated two electromagnets placed at intervals along the main bridge 3, it will be understood that a greater number in association with the main bridge and/or one or more in association with the bass bridge 3' may be employed if desired.

It will be understood that various -m0dific'ations may be made in the apparatus, and combinations of the apparatus, above described and shown in the various figures of the accompanying drawing, without departing from the scope or spirit of my invention, as in the appended claims defined.

I claim:-

1. A musical instrument wherein substantially the entire sound output is translated from electric oscillations, comprising a plurality of variously tuned vibrators; means selective with respect thereto for exciting vibration thereof mechanico electric translating apparatus having portions respectively in spaced relationship to said vibrators and operating in accordance with vibratory variation of such spaced relationships, for translating vibrations of said .vibrators into said first mentioned oscillations; and a vibratile system engaging said vibrators and coupling the same together, said vibratile system having small sound radiating surface.

2. A musical instrument wherein substantially the entire sound output is translated from electric oscillations, comprising a plurality of variously tuned vibrators; means selective with respect thereto for exciting vibration thereof; inechanicoelectric translating apparatus having portions bridge, said support being respectively in spaced relationship to said vibrators and operating in accordance with vibratory variation of such spaced relationships, for translating vibrations of said vibrators into said first mentioned electric oscillations; and means supporting said vibrators, at least a portion of said supporting means being vibratile, and said vibrati1e portion having small sound radiating surface.

3. A musical instrument wherein substantially the entire sound output is translated from electric oscillations, comprising a plurality of variously tuned vibrators; means selective with respect thereto for exciting vibration thereof; mechanico-electric translating apparatus having portions respectively in spaced relationship to said vibrators and operating in accordance with vibratory variation of such spaced relationships, for translating vibrations of said vibrators into said first mentioned electric oscillations; and a vibratile system engaging said vibrators and coupling the same together, said vibratile system comprising a skeleton structure having negligible coupling to surrounding air.

4. A piano wherein substantially the entire sound output is translated from electric oscillations, comprising a plurality of variously tuned strings; percussive means selective with respect .thereto for exciting vibration thereof; mechanico-elcctric translating apparatus having portions respectively in spaced relationship to said strings and operating in accordance with vibratory variation of such spaced relationships, for translating vibrations of said strings into said first mentioned oscillations; and a vibratile system engaging said strings and coupling the same together, said vibratile system having small sound radiating surface.

5. A piano wherein substantially the entire sound output istranslated from electric oscillations, comprising a plurality of variously tuned strings; percussive means selective with respect thereto for exciting vibration thereof; mechanico-electric translating apparatus having portions respectively in spaced relationship to said strings and operating in accordance with vibratory variation of such spaced relationships, for translating vibrations of said strings into said first mentionedoscillations; and a vibratile system engaging said strings and coupling the same translating vibrations of said strings into said first mentioned oscillations; a bridge engaging said strings; and a vibratile support for said wholly formed of strips of relatively small cross-section, whereby the total surface of said support is rendered small.

'7. A piano wherein substantially the entire sound output is translated from electric oscillations, comprising a rim; a plate, strings strung in said' plate; hammers adapted to strike said strings;,a vibratile system of small surface coupling said strings together, said system comprising a bridge engaging said strings, and a plurality of strips of small cross-section, said strips being terminally secured to said rim and engaging said bridge at points intermediate their extremities; and --mechanico-electric translating apparatus having portions respectively in spaced relationship to said strings and operating in accordance with vibratory variation of such spaced relationships, for translating the vibrations of said strings into said first mentioned electric,oscillations.

8. A musical instrument wherein substantially the entire sound output is translated from electric oscillations, comprising a plurality of variously tuned vibrators; means selective with respect thereto for exciting vibration thereof; mechanico-electric translating apparatus having portions respectively in spaced relationship to said vibrators and operating in accordance with vibratory variation of such spaced relationships for translating vibrations of said vibrators into said first mentioned oscillations; a vibratile system engaging said vibrators and coupling the same together, said vibratile system having small sound radiating surface; and acoustic shielding means for reducing the amplitude of residual direct sound output from said instrument.

, 9. A musical instrument wherein substantially the entire sound output is translated from electric oscillations, comprising a plurality of variously tuned vibrators; means selective with respect thereto for exciting vibration thereof; me'chanico-electric translating apparatus having portions respectively in spaced relationship to said vibrators and operating in accordance with vibratory variation of such spaced relationships, for translating vibrations of said vibrators into said first mentioned electric oscillations; a vibratile system engaging said vibrators and coupling the same together, said vibratile system comprising a skeleton structure having negligible coupling to surrounding air; and acoustic shielding means for reducing the amplitude of residual direct sound output from said instrument;

10. A musical instrument wherein substantially the entire sound output is translated from electric oscillations, comprising a plurality of variously tuned vibrators; means selective with respect thereto for exciting vibration thereof; mechanico-electric translating apparatus having portions respectively in spaced relationship to said vibrators and operating in accordance with vibratory variation of such spaced relationships, for translating vibrations of said vibrators into said first mentionedoscillations; a vibratile system engaging said vibrators and coupling the same together, said vibratile system having small sound radiating surface; and means for rendering said vibratile system substantially rigid at will, whereby its couplingaction is substantially eliminated.

11. A piano wherein substantially the entire sound output is translated from electric oscillations, comprising a plurality of variously tuned strings; percussive means selective with respect thereto for exciting vibration thereof; mechanico-electric translating apparatus having portions respectively in spaced relationship to said strings and operating in accordance with vibratory variation of such spaced relationships, for translating vibrations of said strings into said first mentioned oscillations; a bridge engaging said strings; a vibratile support for said bridge, said support being wholly'formed of strips of relatively small cross-section, whereby the total surface of said support is rendered smallyrigid supporting means for said bridge; and selective means for connecting said bridge and said rigid supporting means at will.

12. A piano wherein substantially the entire sound output is translated from electric oscillations, comprising a rim; a plate; strings strung in said plate; hammers adapted to strike said strings; a vibratile system of small surface coupling said strings together, said system comprising a bridge engaging said strings, and a plurality of strips of small cross-section, said strips being terminally secured to said rim and engaging said bridge at points intermediate their extremities; mechanico-electric translating apparatus having portions respectively in spaced relationship to said strings and operating in accordance with vibratory variation of such spaced relationships, for translating vibrations of said strings into said first mentioned electric oscillations; mutually engageable members respectively secured to said plate and said bridge; and selective means for engaging said members at will, whereby said bridge is prevented from executing appreciable vibration.

BENJAMIN F. MLESSNER. 

